Apparatus for stretching fabrics

ABSTRACT

IN APPARATUS FOR EFFECTING MICRO-LENGTH STRETCHING OF WEBS OF MATERIAL TRANSVERSELY OF THE LENGTH OF SAID WEBS COMPRISING AT LEAST ONE PAIR OF CYLINDRICAL ROLLS, EACH OF SAID ROLLS HAVING A SERIES OF CIRCUMFERENTIALLY EXTENDING AXIALLY SPACED GROOVES AND LANDS, MEANS MOUNTING SAID ROLLS IN PARALLEL INTERMESHING RELATION SO THAT THE LANDS OF ONE ROLL EXTENDS INTO THE GROOVES OF THE OTHER ROLL IN SPACED RELATION THERETO, ADJUSTABLE MEANS FOR MOVING THE ROLLS RADIALLY RELATIVE TO ONE ANOTHER TO ESTABLISH THE DESIRED AMOUNT OF EXTENSION OF THE LANDS INTO THE GROOVES OF THE ROLLS, MEANS GRIPPING LONGITUDINALLY EXTENDING SPACED PARALLEL ZONES OF SAID WEB AS THE WEB MOVES BETWEEN THE NIP OF THE ROLLS, AND MEANS FOR ROTATING SAID ROLLS AT A PREDETERMINED ANGULAR RATE IN A DIRECTION TO ADVANCED THE WEB THROUGH THE NIP OF THE ROLLS TO MAINTAIN A MINIMUM TENSION ON THE WEB IN A LONGITUDINAL DIRECTION, THE DISTANCE BETWEEN ADJACENT LANDS OF EACH OF SAID ROLLS BEING NO GREATER THAN 1/10 THE WIDTH OF THE WEB AND SAID LANDS AND GROOVES BEING IN PREDETERMINED INTERMESHING RELATION TO PROVIDE FOR A SUBSTANTIALLY UNIFORM ELONGATION OF THE WEB IN A WIDTHWISE DIRECTION OF AT LEAST 30% OF THE BREAKING ELONGATION OF THE WEB MATERIAL.

Dem 1971 A. E. LAUCHENAUER APPARATUS FOR STRETCHING FABRICS Original Filed March 7, 1966 QEITIISQIIL; WW

United States Patent 3,624,874 APPARATUS FOR STRETCHING FABRICS Alfred E. Lauchenauer, Horn, Switzerland, assignor to Raduner & C0. A-G, Horn, Switzerland Continuation of application Ser. No. 532,397, Mar. 7, 1966, which is a continuation-in-part of application Ser. No. 293,128, July 5, 1963. This application Nov. 18, 1969, Ser. No. 877,670 Claims priority, application Switzerland, July 6, 1962, 8,195/62 Int. Cl. D06c 3/06 U.S. Cl. 26-63 1 Claim ABSTRACT 0F THE DISCLOSURE In apparatus for effecting micro-length stretching of webs of material transversely of the length of said webs comprising at least one pair of cylindrical rolls, each of said rolls having a series of circumferentially extending axially spaced grooves and lands, means mounting said rolls in parallel intermeshing relation so that the lands of one roll extend into the grooves of the other roll in spaced relation thereto, adjustable means for moving the rolls radially relative to one another to establish the desired amount of extension of the lands into the grooves of the rolls, means gripping longitudinally extending spaced parallel zones of said web as the web moves between the nip of the rolls, and means for rotating said rolls at a predetermined angular rate in a direction to advance the web through the nip of the rolls to maintain a minimum tension on the web in a longitudinal direction, the distance between adjacent lands of each of said rolls being no greater than A the Width of the web and said lands and grooves being in predetermined intermeshing relation to provide for a substantially uniform elongation of the web in a widthwise direction of at least 30% of the breaking elongation of the web material.

This application is a continuation of my copending application Ser. No. 532,397, filed Mar. 7, 1966, now abandoned, which in turn is a continuation-in-part of my copending application Ser. No. 293,128, filed July 5, 1963, and now U.S. Pat. No, 3,533,726, granted Oct. 13, 1970.

The present invention relates to the treating of textile material by stretching of the material in a particular manner to impart to the material certain beneficial results which in some cases are exhibited in the material as a result of the stretching alone and in other instances is exhibited when the material after stretching is subjected to various finishing procedures including dyeing, stabilization of dimensions or shape and treatments for imparting wash-and-wear characteristics, crease resistance or shape retention.

It is known that by means of stretching or elongating filiform materials of natural fibers or synthetic polymers during or shortly after the spinning process, it is possible to influence the orientation, density distribution over the cross section of the fibers formed, etc. in a controllable manner. From the literature it can furthermore be seen that effects of various kinds can be obtained, if yarns, twines or other filiform textile material is subjected to elongation treatments on the usual equipment. In Textile Research Journal, vol. 31 (1961), p. 550, it is for example described how by treatment with aminoplast pre-condensates under tension on cotton yarn one obtains lesser strength losses than when the same treatment takes place without elongation. In the American Dyestuff Reporter, vol. 43 (1964), p. 25, it is established that by mercerization of yarns under strong elongation one obtains particularly intensive mercerization effects, but not in the mercerization of fabrics. In Chemie, vol. 55 (1942), p. 12, it is presented that in regenerated cellulose fiber cables the strength can be significantly increased by stretching them out of their natural shape by 15%. There is information about stretching procedures for polyamide fibers in Chemische Textilfasern, Filme and Folien (Chemical Textile Fibers, Films and Foils) by Pummerer, First edition 1953, p. 685.

All these effects could be obtained, as mentioned, only by elongation of individual fibers or yarns parallel to their axis.

By means of conventional elongation procedures, it is not possible to elongate yarns and fibers, present in the form of flat textile products, either parallel to their axis, or to a sufficient extent (up to near the breaking elongation) or with sufficient uniformity over the entire area, and this for the following reasons:

An elongation parallel to the yarn axis within a fiat textile product is possible only when the incorporation (yarn crimp) present in any such flat product and the undulatory course of the yarns to be elongated, caused thereby, is almost completely abolished at least during the elongation, that is, the yarns should take the form of a practically straight line in that direction. But it is prerequisite for this that the mechanical pull which effects the elongation act to a large extent only in one direction within the elongation area (that is the highly elongated area at a given time). But this is not the case in all known elongation devices, The prerequisite for this is a narrow elongation area and an elongation in small regions.

In the conventional elongation procedures one works with large elongation distances, that is a large interval between the points of attack by the force with elongation action (in a tenter frame the elongation distance for example corresponds to the width of the goods). The elongation is therefore not uniform over the entire flat product (for yarns are never quite uniform with regard to their elongation over their entire length. More easily elongatable zones elongate very much, less easily elongatable ones remain extensively unchanged), and moreover the elongation is stronger in the vicinity of the points of attack of the elongating force than at a greater distance from them. From this irregularity in the elongation follows also the impossibility of achieving elongations up to near the breaking elongation. The more easily elongatable and more strongly elongated portions of the fibers and yarns tear before the remaining ones are sufficiently elongated.

Conventional elongattion procedures have additional drawbacks: As a result of the large elongation areas they require a large expenditure of force, and they make possible no high elongation velocities. But in the higher velocity ranges the breaking load of most fibers increases with increasing elongation velocity, without the breaking elongation decreasing accordingly (compare for example Journal of the Textile Institute, vol. 50 (1959), pp. 41- 54). At the high elongation velocities one can therefore for example, in controlling the elongation process by limiting and steering the acting mechanical force, steer and differentiate the elongation better and thus achieve higher elongations with greater safety margins when working with very high elongation velocities, such as are not attainable at all with conventional elongation procedures. The sliding of the yarn components on each other, which counteracts the elongation of the individual fibers, is also diminished by very high elongation velocities, and effects can be achieved which are understand ably not possible with a 501000 times smaller elongation velocity.

An ideal elongation procedure should fulfill the following conditions, if it is to make possible an industrially useable modification of properties of fibers in the form of fiat textile products in an economical manner:

(1) The elongation must take place over small to infinitely small elongation distances, that is the points of attack of the force effecting the elongation must lie near to infinitely near each other, so that each zone of a yarn or thread experiences exactly the same elongation.

(2) The elongation must take place almost completely parallel to the yarn, if possible even to the fiber axis. This requires that within the elongation area, an elongation occurs practically only in the direction of the thread system to be elongated, whereas in the others there may appear at most a slight elongation relative to the elongation effect in the direction of elongation, that is an only small mechanical pull compared to the force with elongating effect. For this reason the elongation area in addition to the elongation distance must be small.

(3) Elongations of at least 30%, preferably however at least 50% of the breaking elongation of the flat product in question in the elongated direction must be attainable. For this the elongation must be uniform over the entire yarn length, as mentioned.

(4) The elongation velocity should be high and at least per second, but preferably 50% per second and more. The elongation should therefore be almost abrupt.

It was now found that on fibers or yarns which are present in the form of fiat textile products, it is possible to improve properties, particularly also increase the mechanical strength, by elongation essentially parallel to the yarn or fiber axis, by subjecting the flat product preferably over the entire area, with at least transitory abolition of the incorporation of the thread system to be elongated to an at least one-stage elongation in small zones whereby the force which effects the elongation acts at any given moment only within a narrow strip of the goods width and extensively only in the direction of the thread system to be elongated, and the points of attack of the force with elongating effect lie near to infinitely near each other, whereby the elongation amounts to at least 30%, preferably however at least 50% of the breaking elongation of the flat textile product in the direction to be elongated and the elongation velocity to at least 10% per second, but preferably at least 50% per second, and whereby during the elongation the intermolecular cohesion of the elongated material is preferably reduced, and is brought back to at least the original status again after the elongation has taken place.

A particular advantage of the present invention is achieved in the treatment of textile materials consisting wholly or in part of natural cellulosic fibers, such as cotton to impart to the fabric by stretching thereof characteristics the advantages of which are exhibited after the fabric has been subjected to finishing effects such as washand-wear properties, dry and wet crease recovery, dimensional stability and the like particularly when such treatments are effected by crosslinking. Prior to the present invention the treatment of cotton fabrics to impart such finishing effects has resulted in very high losses of the tensile strength, sometimes reaching 60% or more of the original tensile strength of the fabric. Similar high losses sometimes of even greater magnitude have been suffered in the abrasion and tearing strengths of the treated fabric compared with the original fabric.

Common practice in such treatment of fabrics containing cellulosic fiber is to apply improving agents to the textile material by padding, squeeze it and dry it at least partly, and finally to crosslink, as a rule by subjecting it to a heat treatment. In other cases crosslinking is effected when the textile material still is in a swollen state, i.e. before squeezing.

It has been proposed to tension the textile material during the crosslinking step, for instance by stretching it, in the case of textile fabrics, in tenter frames, the

4 stretching being carried out by pulling the fabric from end to end, i.e. lengthwise, or at both selvages, i.e. weft- Wise. Such a process is for instance described in the U.S. specification 2,977,665. As the figures listed there show, improvement of the tensile strength is generally speaking below 10 Many tests carried out in textile finishing mills have shown that processes based on stretching fabrics by conventional methods in the presence of crosslinking agents, if applied in the mill, do not offer advantages which would make their application seem worth while. The reason for this is related to the fact that the conventional stretching processes consist in stretching a fabric in the direction of the filling (which usually is the weaker direction and hence would profit most from a decrease of tensile losses) by pulling it at both selvages. In such processes it is rare to produce a stretching action which is uniform over the whole length of the yarn system to be stretched due to the inevitable lack of uniformity of individual yarns (which results in a varying degree of stretching) on one hand, and due to the easily detachable differences in the degree of stretching from the selvages to the middle of the fabrics on the other hand (the degree of stretching is higher near the selvages than in the middle). Finally, it is impossible to stretch by such methods to an extent which could result in a more than marginal decrease of tensile losses.

Since the degree of stretching is extremely important for the improvement of the tensile strength, and since there is a lower limit below which no appreciable improvement at all is obtained, the only effect achieved under these conditions may be a more uniform tensile strength of the fabric components. The weaker components are stretched more and hence show less loss of tensile strength after cross-linking than the formerly stronger parts, which are hardly affected by the stretching process and thus exhibit a normal loss of strength. This also may explain why in laboratory trials where tests are made with shorter strips of fabrics, much better results are obtained than in the mill.

In a broad sense it is an object of the present invention to provide a substantially irreversible rearrangement of yarns and/or yarn or fiber components produced by stretching said textile material, not as usual by mechanically pulling between distant points, for instance between selvedges of a fabric, but by pulling in very small increments, i.e. by dividing the stretching area into small or even infinitely small areas, within which the stretching is uniform. Such stretching, for conveniene herein, sometimes will be referred to as micro-length stretching even though the increments in some instances may be so small as accurately to be defined as micro and in other instances may be larger than what is usually called micro. Such stretching also sometimes will be referred to herein as small area stretching. Methods for producing small increment stretching may, for example, consist in causing the textile material to form curves or undulations of small length perpendicular to its original surface thus causing an increase in the dimension of the fabric while the dimensions measured in the plane of the original surface remain substantially unchanged.

A more specific object of this invention consists in producing on textile material, preferably when it is in an at least slightly swollen state, a rearrangement of yarns, fibers and components thereof by means of uniform stretching to at least 30%, and preferably to 50% of the elongation at break of said textile material in the stretched direction. The stretching is carried out in small to infinitely small distance as stated above. In connection with fabrics containing cellulosic fibers the stretching is carried out prior to any crosslinking of the cellulose fibers which may be performed to improve Wash-and-wear, crease recovery and similar characteristics.

It is a further object of this invention to provide a method and apparatus for performing the micro-length or small area stretching. A preferred form of such apparatus is illustrated herein. Such preferred apparatus is designed to stretch a web of fabric transversely of its width and consists basically of a pair of intermeshing circumferentially grooved rolls or bowls, devices for holding the edges of the web and provision for adjustment of the degree of intermeshing of the rolls to predetermine the amount of stretch to be imparted to the width of the fabric extending between the edge holding devices.

The preferred form of apparatus and the method of utilizing the same is illustrated in the drawings forming a part of this specification.

In the drawings:

FIG. 1 is a diagrammatic side elevational view of the apparatus;

FIG. 2 is an end elevational view of a portion of the apparatus looking in the direction of the arrows 2-2 in FIG. 1; and

FIG. 3 is an enlarged fragmentary sectional view of a portion of the apparatus shown in FIG. 2.

In case a small zone elongation is carried out crosswise to the fabric web by means of grooved cylinders which engage with each other, it is possible to exert control by limiting the depth of penetration or by keeping the pressure with which the grooved cylinders are pressed against the textile web lying between them constant, or else by a combination of the two methods. As a rule the grooved cylinders should not touch anywhere along their entire length, since otherwise the penetration depth and with it the degree of elongation cannot be varied arbitrarily. It has been found expedient to hold the edges of the fabric web by suitable devices, in order to prevent having them escape towards the middle of the web as a result of the pull exerted transversely to the web (through this the elongation on the two sides of the web would be less than in the middle). The holding of the edges can be done in different ways: One can spread the web widthwise directly before, possibly also after the contact with the cogged cylinders by means of edge-guiding (gripping) devices known as such. A very simple method for guiding the edges consists in that at least on one of grooved cylinders engaging with each other in pair there are inserted into those two regions in which the fabric edges run, band-shaped or other articles of suitable form into the grooves which prevent the edges of the web from a lateral sliding towards the middle of the web by means of a high frictional resistance, or actually clamp the edges of the web tight by contact with a land or lands of the opposing cylinder. The band-shaped articles expediently consist of a material which can be elastically compressed, that is of rubber or porous rubber of elastically compressible synthetics, which possibly contain pores, that is they may be in the form of foam, or of combinations of elastic and less elastic material. The cross section may be round, angular or adapted to the form of the groove of the cylinder, or have a form which combines easy compressibility of the highest possible resistance to lateral sliding, for example by means of cavities. On the other hand one may also diminish or prevent the lateral escaping of the goods web edges to a great extent through the form of the lands of the grooved cylinders and their distances from each other. Lands standing close by each other, and lands which have a not very rounded cross-section, but rather an angular one, prevent the lateral sliding particularly well, althrough, of course, there may not be any cutting edges present.

The surface of the grooved cylinder may consist of metal or of another material, which almost completely retains its form under the conditions of the elongation, and at most is slightly compressed during the elongation, that is preferably has a hardness of at least 100 Shore A. A favorable sliding resistance of the surface material above all also relative to goods which contain water, is important. Friction values of 0.2-0.7 have proven to be favorable (friction value of moist textile material on the surface material in question).

The distance between the lands of the grooved cylindersif the elongation is still to be a small zone elongationmust amount to at most preferably at most of the width of the fabric web (that is the elongation zones must be at least 10 or 20 times smaller than in the conventional elongation by pulling on the two edges of the web), and should amount to at most 10 cm., preferably however at most 5 cm. In the preferred mode of execution the distance of the lands on the grooved cylinders is 1 to 2.5 cm., at any rate at most 3 cm. In some instances, particularly when elongation is to be carried out in successive stages, it may be preferred to so shape and space the lands that the length, in the direction of elongation, of the portions of the fabric which, during elongation, are in contact with the surfaces of the lands is as great as or greater than the length of those portions which extend between lands out of contact therewith.

When the elongation is done in several stages, then different land forms and spacing on the rolls may, if desired, be used in the individual stages. Arrangements have also been used successfully in which three similar grooved cylinders which engage in each other effected a small area elongation in two stages, or in which several small cylinders engage in a larger one. In any multi-stage elongation between grooved cylinders it is important in order to achieve maximum elongation effects, that the flat product is made uniformly smooth over the entire width after each passage between grooved cylinders that engage in each other, by means known as such, for example separating cylinders, spiral separators etc., in other words, the lengthwise fluting caused by the lands is pulled flat before the web runs into the next pair of grooved cylinders. Through this is achieved on the one hand a uniform second elongation stage, and furthermore one achieves that the lands and grooves of the second pair of cylinders do not touch the goods at the same places as the first pair of cylinders.

Before the fabric, elongated between grooved cylinders, is rolled up or put down it should likewise be pulled flat, so that no folds are fixed in it during the rolling up, and the elongation effect is not detrimentally influenced.

Referring now to the drawings apparatus of the type generally described above is shown in somewhat diagrammatic and fragmentary form. In FIG. 1 a web 10 of fabric is supplied from a roll 12. The web 10 is guided over a spreading roll 14, which as noted above, may be a spirally threaded roll or other equivalent structure. As shown particularly in FIG. 2 the spreading roll 14 is provided with oppositely handed spiral threads 16 and .18 which extend outwardly from the middle of the length of the roll whereby to frictionally engage the fabric and to smooth out any wrinkles therein. Such relatively minuscule amount of stretching as may be caused by spirally threaded rolls such as roll 14 or equivalent smoothing devices such as bowed rolls, is not to be confused with the accurately controlled extensive and positively produced stretching which is the subject of the present invention.

After passing over the smoothing roll 14 the web 10 is guided into engagement with a pair of intermeshing circumferentially grooved rolls 20 and 22. The lower roll 20 is driven, by means including a gear 24 fixed to the shaft 26 upon which the roll 20 is fixed, at such peripheral speed as may be desired to advance the fabric web 10 through the machine. The upper roll 22 need not be driven but in any event is mounted for adjustment toward and from the roll 20 whereby to establish the desired degree of intermeshing of the rolls 2t) and 22. The means for adjustment of the upper roll 22 is not shown herein and it may provide yielding or fixed adjusted position as desired. For example air or hydraulic fluid cylinders may be arranged to press the roll 22 towards roll 20 and the amount of air or other fluid pressure applied may be predetermined in such manner as to provide the desired degree of stretching. Otherwise, devices such as screw-jacks may be used to move the upper roll 22 into any desired fixed relation with the lower roll 20.

After the fabric leaves the pair of rolls 22 it may be smoothed, as by a spirally threaded spreading roll 28 similar to the spreading roll 14, and conducted to such further processing or winding-up as may be desired. As shown in FIG. 1 the web 10 may be subjected to further small-area stretching by means of a second pair of rolls 30 and 32 which may be similar to or identical with or quite different from the first pair of rolls 20, 22. When the second pair of rolls 30, 32 is used the web 10 of fabric should be subsequently smoothed as by another spreading roll 34 which may be similar to the spreading roll 14. Obviously additional pairs of small-area stretching rolls may be provided whereby the fabric web .10 may be successively stretched to the desired degree.

As shown in FIGS. 2. and 3 the stretching rolls 20 and 22 are circumferentially grooved rolls which have lands 36 and 38 respectively and grooves 40 and 42 respectively. Preferred contours for such grooves and lands have been discussed above and the particular contours shown in FIGS. 2 and 3 are merely illustrative.

In FIGS. 2 and 3 there is shown one form of edge gripping device of the type discussed generally above. Thus a pair of rings 44 made of rubber or other suitable elastomeric material is shown associated with the lower grooved roll 20. The rings 44 are not only yieldable in cross-section but also, preferably, are stretchable in circumferential direction whereby the rings may be positioned in any of the grooves 40 of the roll 20 to cooperate with the longitudinal edges of a fabric web 10 of any width which may be encountered, within the full-length capacity of the roll 20. The cross-sectional shape of the rings 44 may be circular, as shown in FIGS. 2 and 3 or may be varied as noted above. It is preferred that the rings have cross-sectional dimensions such that they will be firmly engaged by the opposing land 38 of the upper grooved roll 22 in all positions of adjustment of the intermeshing relationship of lands and grooves, thus to be operative whether the fabric web 10 is to be only slightly stretched between its edges or is to be extensively stretched as the result of deeper intermeshing of the lands and grooves.

While a single pair of rings 44 has been shown in FIGS. 2 and 3 it will be recognized that two or more pairs of rings may be provided for additional gripping effect. Also, the rings 44 may be positioned on the upper grooved roll 22 if so desired and if two or more pairs of rings 44 are used they all may be positioned on one or the other of rolls 20 and 22 or certain of them may be divided between the grooved rolls.

As clearly shown in FIGS. 2 and 3 the rings 44 serve to grip the edges of the fabric web 10 as closely to the extreme longitudinal edges 46 thereof as may be desired, thus minimizing waste of edge portions which, lying outside the active region of the intermeshing rolls 20 and 22, will not be subjected to the stretching operation.

The small-area or micro-length stretching effected by the apparatus illustrated in the drawings is that which occurs in the transverse lengths of the fabric web 10 which extend between adjacent lands 36 of roll 20 and 38 of roll 22. The more closely said lands are spaced on the grooved rolls 20 and 22 respectively the smaller each small-area or micro-length will be. Preferred ranges of dimensions have been discussed above.

The magnitude of the stretch effected by passing the Web 10 through the intermeshing rolls 20 and 22 with the edges thereof gripped by the rings 44 is, of course, determined by the depth of penetration of the lands 36 and 38 into the respective grooves of the rolls 20 and 22. As will be apparent, the undulating path which the fabric web 10 is forced to take is longer than the path lying in the original plane of the web 10 and the web thus is stretched in a manner which is substantially uniform throughout the width thereof which lies between the edge-gripping devices 44.

When it is desired to carry out the small-area or microlength stretching in two or more steps the additional pairs of intermeshing rolls, such as the rolls 30 and 32 shown in FIG. 1 preferably are also equipped with edge gripping devices, such as the rings 44 illustrated and described herein. \As noted above it is much preferred that the intermeshing rolls 20, 22 as well as subsequent pairs of rolls, when used, do not intermesh to such an extent as to grip the fabric web between the tops of the lands and the bottoms of the grooves since such gripped areas may not receive the desired uniform amount of stretching. This is particularly true when the material from which the lands are made is relatively unyielding as is the case when the lands are made of metal or other hard material. In some instances the lands on one or both of the grooved rolls may be relatively yieldable or, indeed one of the rolls may be a plain cylinder of yieldable material, in which case the portions of the fabric web gripped by such yieldable material may receive stretching which is reasonably comparable with the stretching imparted to the ungripped portions extending between adjacent lands.

The textile material of the Web 10 may be wholly or in part of cellulosic fibers and specific examples of the treatment of such textiles will be given. However, certain benefits are achieved with other types of textiles, for example, containing synthetic or artificial fibers such as polyesters, polyamides, regenerated cellulose or cellulose derivatives. Also, the textile material may contain treating or finishing materials such as for example dyestuffs, colored or dyestuff-forming pigments, agents capable of reticulating (i.e. cross linking) the fibrous material, means for reducing the inter-molecular cohesion, such as for example swelling agents, moreover agents which influence the friction between the individual fibers. Therefore the elongation may for example be carried out in the presence of swelling agents and friction-increasing agents, so that sliding between the macromolecules that make up the fiber is favored, the slipping of fibers on each other is reduced.

As mentioned, the elongation treatment according to the procedure can be so carried out that the inter-molecular cohesion within the fiber is loosened during the treatment, in that the textile material for example may contain weak to strong swelling agents, or in that the cohesion between the macro-molecules is loosened by physical means (for example heat). After, if so desired also during, the elongation treatment, the intermolecular cohesion of the material is again restored to at least the original state.

The elongation treatment can be carried out above, below or at room temperature and when carried out in successive stages, certain treatments may be made between stages. While it is preferred to have the elongation substantially or exactly parallel with the thread system of the fabric, in certain cases it may be desirable to have the mechanical strain which effects the elongation exerted not exactly parallel to the thread system, for example in woven fabrics, but at an acute angle to it. In this case, for example for small area elongation in the woof direction, the angle between the warp and woof thread system in the fabric can be brought temporarily from deg. to an angle of for example 7585 deg. before the treatment by means of grooved cylinders, or the elongating device can be so fashioned that it exerts an elongation under a constant or variable angle relative to the thread system to be elongated.

The elongation treatment according to the invention can in principle be carried out during any stage of the finishing (which means between weaving and making-up operation). It can also be carried out before, during, between or after de-sizing, washing, bleaching, dyeing, swelling (for example caustic treatments in the case of cellulose fibers), finishing treatments, mechanical deformations, etc. Customarily however the elongation treatment will be carried out before any fixation treatments which aim at bringing about a certain permanent configuration of the flat product (or of the yarns and fibers) or wash-fast dimensional stabilization of the same by thermal fixation, compressive shrinkage and/or reticulation. In cellulose fibers for example a small area elongation is hardly effective after a permanent cross linking of the cellulose chains.

Depending on the intended purpose it is advantageous in many cases to fix effects brought about by small zone elongation (for example the fiber and yarn configuration) by means of fixation treatments, that is, to make them permanent. In other cases, for example when the breaking load of material is to be increased or its dyestuff absorption reduced, the incorporation transfer can be completely or partly abolished. Examples will be listed later.

As attainable effects are to be mentioned:

Increase in the mechanical strength, particularly the breaking load; extensive to complete transfer of the incorporation from one thread system to the other without significant loss of area or even with a gain in area (the procedures known to date without exception caused appreciable to great losses in dimension) and with strength increase for the elongated thread system (in the conventional procedures the strength at best was kept) whereby this transfer of the incorporation is transitory or can be made permanent, depending on the procedural conditions chosen (examples of such effects: elasticity increase in the thread system to which the incorporation was transferred, better napping ability of textile flat products, in which the incorporation was transferred according to the procedure while improving the textile and tear strength of the weft from which the crimp or incorporation has been transferred to the warp); improved printing effects based on the fact that a fabric is printed in which the incorporation was previously transferred extensively from one thread system to the other, whereupon the incorporation is again transferred back to the first thread system to a large extent; modification of the dyestuff absorption of thermoplastic fibers while they are in the form of a fabric; increase in the elasticity; reduction of the breaking elongation; wash-resistant selective rearrangement of distribution pattern of components of fiber blends (blended yarns or plied yarns) in the elongated direction; permanent deformations with considerable gain in area; increased saponifiability of at least the surface of thermoplastic fibers, such as for example of fibers of acetylated cellulose; achieving modifications in the surface of the fibers by making the fiber superficially brittle and subsequent elongation in small areas, through which it is possible to bring about a feazing or cracking of the fiber surface (by brittleness of the surface is understood here the reduction in the breaking elongation of the inner fiber layers, whereupon the fibrous material is subjected to a small area elongation which is higher than the breaking elongation of the outer, but lower than the breaking elongation of the inner fiber layers); crimping effects through small area elongation particularly between grooved cylinders, whose temperature lies near the fixation temperature of the thermoplastic fiber material in question, preferably followed by wet treatments at raised temperatures, on occasion also dyeing treatments and fixation treatments.

The elongation procedure according to the invention can also be used to free yarn intersections or fiber junctions which have become immobilized in previous treatments of textile products. This results from the abolition, according to the invention, of the incorporation of the elongated yarn system, since the contact points between the two yarn systems are strongly influenced thereby, and above all the area of surface contact between yarns is reduced at least temporarily through extensive elimination of the looping of the yarn systems about each other. This is not possible with conventional elongation procedures,

or much less so, because the incorporation is at best displaced up to an equilibrium for the reasons described, and also because particularly in the case of immobilized yarn intersections the friction between the yarn systems during elongation with large elongation intervals and areas is very high and the elongation over the elongation interval is therefore very irregular.

The elongation treatment according to the invention can moreover be used for the preparation of fiat products with accurately pie-determinable extensibility. For the reinforcernent of plastic products by fiat textile products it is, for example, necessary to attune the extensibility of the plastic and that of the flat product to be used for the reinforcement accurately to each other, for only then can reinforcing effects be achieved at all. In this the extensibility of the flat product must of course be uniform over the entire surface. As a result of the prevously explained causes one obtains with conventional elongation procedures neither a sufficiently uniform nor a suificiently strong elongation to fulfill these requirements, nor can the elongation be steered so precisely that an extensibility of accurately pre-determinable level could be achieved reliably with sufficient operating certainty.

The small zone elongation according to the invention may also serve to achieve effects by elongating fibers in a strongly swelled state, such as they are customarily attainable only in the treatment of yarns. For example cotton can be treated with lye having mercerization strength or with strong acids, and can be subjected to a small area elongation before and/or during and/or after the swelling. Since the elongation takes place parallel to the yarn or fiber axis one obtains effects which cannot be achieved with conventional procedures and devices, but can be in the treatment of individual fibers or yarns.

Above all in fibers with relatively high swelling capacity (for example in cellulose fibers) it is expedient to carry out the elongatioi'i treatment when the textile material is at least slightly swelled, for example when it is moist to wet.

As was mentioned prevously, the small zone elongation according to the invention may take place in any state of finishing of the textile goods in question, expediently however before a fixation treatment which intends a more or less permanent fixation of the dimensions of the textile material and/ or the configuration of the yarns and fibers.

Before, during, between or after small zone elongation treatments it is possible to deposit or incorporate polymer substances or produce them in situthrough polymerization, graft polymerization, polycondensation, or cause functional groups of the textile material or of individual components to enter into reaction, to loosen or split existing bonds between molecular chains (permanently or only transistorily), or in general modify fibers or fiber components chemically, deform them mechanically or bring about changes in the fiber surface.

The small zone elongation according to the invention is preferably carried out over an entire area, but if desired may also occur only locally.

The following examples serve to illustrate the procedure according to the invention when practiced on textile materials of typical synthetic fibers and some attainable effects, however without laying claims to completeness or limiting the subject of the invention.

EXAMPLE A A cretonne (17/.7 thread per cm.) of ethyleneglycol terephthalate, staple fiber yarn, was treated, after washing, as follows:

Sample a: Small zone elongation in woof direction, superficial hydrolysis, dyeing;

Sample b: Superficial hydrolysis, dyeing;

Sample c: Small zone elongation in Woof direction, dye- Sample d: Dyeing.

Small zone elongation: In two stages between grooved cylinders, in which the pressure on the goods was kept constant by pneumatic means, goods previously finished with non-ionogenic softener. Elongation while wet, at room temperature. The elongation was 65 of the breaking elongation, the elongation velocity was 100% per second.

Hydrolysis: For 1 hour at 80 deg. while maintaining the initial dimensions of the samples. Addition of a polyglycol to mediate solution (10 gm./liter).

Dyeing: With 3% (referred to weight of the goods) Disperse Blue 60 (Colour Index Prototype), dyestuif produced by the ICI, Manchester, England, 2 ml./l. 75 %ual. acetic acid and 5 gm./l. o-phenylphenol as carrier.

The samples a and c elongated in small zones showed a significantly deeper dye absorption than the analyogously treated samples b and d not elongated in advance. The small zone elongation caused an increase in the tearing resistance in the elongated direction by 7% and an increase in width of 6% The strength increase remained the same if a thermal fixation was performed after the elongation.

As a result of the fact that the incorporation was almost completely transmitted to the warp threads after the small area elongation, the goods exhibited high elasticity in the warp direction.

NOTE: In the case of flat products from fibers with high elastic component in the breaking elongation, the degree of elongation (in percent of the breaking elongation) cannot be derived from the mere dimension enlargement in the elongated direction. In this case the degree of elongation was determined by means of a band-shaped material with practically inelastic behavior, which was placed on the goods in the direction of elongation and elongated with them.

EXAMPLE B Taffeta (56/36 threads per cm.) of Nylon 6.6 was treated, after washing, as follows:

Sample a: Small zone elongation, dyeing with dispersion dyes;

Sample b: Dyeing with dispersion dyes without small area elongation;

Sample 0: Small zone elongation, dyeing with acid dyes.

Sample d: Dyeing with acid dyes without small area elongation.

Small zone elongation in the woof direction: Between grooved cylinders while wet, elongation 65% of the breaking elongation, elongation velocity 50% per second. Increase in width 10%.

Dyeing: With dispersion dye, 2% Disperse Blue 60 (Colour Index Prototype), 4% acetic acid, 30 %ual., dye with boiling for 1 hour.

Dyeing: With acid dye. 4% acid red 85 (Colour Index Prototype), 4% acetic acid, 30 %ual., dye with boiling for 1 hour.

In both cases the samples previously elongated in small zones showed deeper dye aflinity than those not elongated.

The following examples relate to the use of the present invention with fabrics made from cellulose-containing yarns.

EXAMPLE C A cotton poplin (36/18 threads per French inch) was dried after the desizing, bleaching and dyeing to 40% residual moisture and subjected, without cooling (fabric temperature 80 deg.) to a small area elongation in the woof direction (cogged cylinders, elongation velocity 200% per second, elongation 80% of the breaking elongation). The woof of the poplin consisted of a twine whose twine rotation corresponding almost completely to the rotation of the two individual yarns, but exhibited opposite direction of rotation. The elongation in small zones, during which the woof incorporation disappeared almost completely, whereas the incorporation of the warp increased, therefore was effective not only parallel to the yarn axis, but also extensively parallel to the fiber axis.

The material was subsequently dried. The tearing resistance of the poplin rose by 25% in the woof direction due to the small zone elongation.

EXAMPLE D The sample poplin as in Example C was treated after the desizing and bleaching with lengthwise tension in lye having mercerization strength (30 deg. Beaume) whereby the elongation in small zones was carried out in 3 stages in the Woof direction by means of grooved cylinders after an action interval 'of 60 seconds. During the elongation the incorporation of the woof yarn disappeared-completely, that is the elongation in the lye-swelled state occurred parallel to the yarn axis and extensively parallel to the fiber axis. The material was subsequently washed out, neutralized and rinsed.

The goods thus treated showed at least as good a mercerization lustre as goods which had been made of yarns mercerized on a yarn mercerizing machine. The area obtained was 5% larger than in goods not elongated in small zones, but otherwise treated the same.

When the fabric was freed of swelling agent without significant reduction in the width obtained during the small zone elongation, and dried, then the fabric showed high lengthwise elasticity. The Woof had practically no incorporation anymore. The woof tearing strength of the goods was 20% higher than in goods not elongated in small zones, the gain in area was 8%.

A section of the goods, and an analogously treated sample, however not elongated in small zones, were simultaneously reticulated with gm./liter di methylolpropylene urea, '25 gm./liter polyethylene softener and 12 gm./liter zinc nitrate. The fabric elongated in small zones had a crease recovery of 270 deg. (sum of warp and woof, method: AATCC 66-1959) and a Wash- & Wear-Effect of 4-5 (determination according to AATCC 881961), no loss in the strength, whereas the section which had not been elongated but otherwise treated the same exhibited a loss of 35%, with the same crease angle and the same Washand Wear-Effect, a sample which was not elongated and not mercerized had a 40% loss.

A section of the same poplin was subjected to a small zone elongation in the woof direction between cogged cylinders before the mercerizing treatment, then mercerized as stated. In the subsequent reticulation this section likewise showed no strength loss with otherwise the same properties as the other reticulated samples.

The process according to the invention when applied to fabrics containing cellulose enables (as opposed to known processes applying tension) stretching not only in the presence of crosslinking agents, i.e. immediately prior to or during crosslinking, but also stretching without any additional step during, after or prior to known treatments such as washing, bleaching, dyeing, caustic treatments and so on. Afterwards the textile material may be dried while maintaining substantially the dimensions obtained by stretching in the stretched direction and then crosslinked conventionally by padding in or applying the crosslinking solution, drying, again substantially maintaining the dimensions obtained by micro-length stretching, and curing. In many cases this is an advantage, since stretching during crosslinking i.e. in the presence of the crosslinking agent is known to result in a stiff and boardy hand. Micro-length stretching according to the invention may, however, also be carried out in the presence of the crosslinking agent, i.e. immediately prior to crosslinking-In every case substantially better mechanical properties, particularly better tensile and tearing strength are obtained.

The conditions applied during micro-length stretching of cotton materials for improving final tensile and tear strengths after crosslinking should be so adjusted to obtain an extension of the textile material in the direction to be stretched of at least 30%, preferably at least 50%, of the elongation at break, i.e. What the extension is when the same material is subjected in the same device to conditions under which it tears not only in one, but in many micro-length stretching areas. Generally speaking, it may also be said that the reduction of the extension at break (measured conventionally using strips) caused by microlength stretching, determined by measuring the extension at break immediately prior to and immediately after mirco-length stretching (without intermediate crosslinking treatment or other treatments affecting extension at break) should be at least 30%, preferably 50% or higher, if a substantial improvement of the tensile strength after crosslinking (as compared to material crosslinked conventionally in more or less slack state) is to be obtained. Under optimum conditions the cotton textiles after micro-length stretching in wet state, have been observed to have a tensile strength (measured wet or after drying, without crosslinking) of or more, higher than immediately before the stretching, determined under identical conditions.

To increase the dimensional stability of textile material treated according to the present invention, wet treatments may be carried out after crosslinking in known manner, the material may be mechanically shrunk, or crosslinking may be carried out in several steps by first precrosslinking under tension and then stabilizing the dimensions obtained by a second crosslinking treatment.

If the dimension increase brought about by the stretching process for some reason is undesirable, known treatments, (mechanical or chemical, shrinking treatments generally speaking) resulting in a decrease of dimensions in one or both directions may be applied prior to or after micro-length stretching, i.e. one may either reduce an increase of the dimensions caused by stretching by subsequent shrinking treatments or stretch material which had been shrunk previously, restoring for instance by stretching the dimensions the material had prior to shrinking.

Micro-length stretching may as mentioned above be applied to yarns or textile fabrics to the full extent or incrementally at any stage of textile processing or carried out (or be completed) during the crosslinking step, i.e. it may proceed in steps, stretching not being done in one but in several steps, which if desired may be separated by a lapse of time and processing treatments. The same or different mechanical means may be used in different steps. It has for instance been found that less mechanical pull is re quired to obtain a given degree of elongation if the same material had been subjected to stretching to a similar extent at an earlier stage.

As mentioned earlier, micro-length stretching may be preferably applied to cellulosic textile material which is in an at least slightly swollen state. One may for instance subject the material to micro-length stretching after or during the usual wet treatments preceding crosslinking (bleaching, dyeing, mercerizing and so on) Without intermediate drying, i.e. in the presence of agents having a swelling action on cellulose fiber-s such as for instance water, caustics, acids or salt solutions.

If micro-length stretching does not form part of the crosslinking treatment, but is applied exclusively at an earlier stage, then it is important either to avoid treatments between micro-length stretching and crosslinking which could affect the rearrangement of yarns, fibers and components thereof brought about by micro-length stretching or to repeat micro-length stretching.

At any stage, particularly immediately prior to causing the crosslinking agent to react with cellulose, the textile material may be subjected to conventional mechanical deformation such as embossing between plain or engraved bowls, which may be heated or cold, and the mechanical deformaiton may if desired be rendered fast to washing by the crosslinking step.

The term crosslinking (sometimes also referred to as reticulation) as it is used throughout the present application includes the step of increasing the intermolecular cohesion within the textile material after stretching, by

causing covalent bonds to form between macromolecular chains, or by forming in situ or introducing into the fiber structure agents capable of increasing the number of noncovalent bonds or cholates, or if desired, by subjecting the textile material to physical treatments such as radiation or heat treatments capable of increasing the intermolecular cohesion of the fiber-s present in the textile material.

As examples for crosslinking agents are mentioned:

Thermosetting resins of the reactant type (applied in the form of precondensates or components) obtainable from nitrogenous compounds containing amidic nitrogen (-CO-NH-) and monoor polyfunctional carbonyl compounds, particularly aldehydes (examples: reaction products from formaldehyde, glyoxal, acroleine and urea, cyclic alkylene ureas, ureins, triazones, or other heterocyclic compounds containing -NHCONH- groups): monomeric or polymeric crosslinking agents reacting through aldehyde groups, particularly aldehydes of low molecular weight such as those mentioned above, applied in free form or as derivatives such as acetals, enol ethers, polymers, which under the crosslinking conditions used are per as capable of crosslinking cellulose or giving off compounds capable of doing so; dior polyfunctional crosslinking agents containing epoxy-, isocyanate-, vinylsulfoor other vinyl compounds capable of reacting with at least two cellulosic hydroxy groups; halogen compounds such as polyhalides, halohydrins, dicarboxylic acids in free form or in the form of derivatives; dior polyfunctional onium compounds (sulphonium, phosphonium, oxonium); reaction products of two carbonyl compounds such as ketones with aldehydes of low molecular weight (in particular oxy-methyl substituted ketones), all the compounds mentioned being brought to reaction preferably in the presence of suitable agents having a rate-increasing action (acid, basic, potentially acid or basic catalysts, radicals or radical producing compounds, radiation), and if desired also in the presence of known agents having a light to strong swelling action or influencing interfiberfriction, known finishing agents, dyestuffs, pigments.

Crosslinking reactions caused by exposing the prestretched textile material to physical/chemical influences such as heat treatments, irradiation (high energy radiation), by substitution reactions, graft polymer formation, formation of polymers in situ or deposition of polymers within the fiber, are within the scope of the present application if such crosslinking treatments per se increase the elasticity of the cellulosic fibers (in dry state) and decrease its extensibility.

If the crosslinking agent applied is a chemical compound, it may be applied as usual from solutions, disper sions of emulsions or from gas phase, crosslinking taking place after or during evaporation of volatile solvents (e.g. water), i.e. in a de-swollen or only slightly swollen state of the cellulose, or in the presence of swelling agents, i.e. when the cellulose is in a swollen state. In both cases suitable catalytic agents may be used as mentioned above to increase the rate of the reaction.

As mentioned earlier, micro-length stretching may-if it has not been completely carried out earlier, be effected or completed immediately prior to crosslinking. It is also possible to cause after a preliminary micro-length stretching treatment only partial crosslinking, i.e. a low degree of crosslinking, and to effect further crosslinking at a later stage, for instance after the material has been subjected to further stretching.

After the cellulose has been crosslinked, stretching treatments are of no use or even harmful. On the other hand known finishing treatments such as washing, paddingon of finishing agents, softeners, pigments, compressive shrinkage treatments and of course making-up may be carried out as usual.

If particularly high creasing angles are desired or for other reason a second crosslinking treatment may be effected after first crosslinking the stretched material under relatively mild conditions as to the concentration of the crosslinking agent and crosslinking conditions.

The stretching may be effected in several steps, with or without conventional finishing treatments between the several steps. Preferably the crosslinking agents are applied near the final stretching step, either immediately before or immediately after the step. The material may be mechanically deformed after the final stretching step, and the deformation may be rendered fast to washing by cross-linking.

Further Examples (Cellulosic Textiles) All testing results are listed in table I. In all cases micro-length stretching resulted in an extension of more than 50% (usually 6080%) of the extension at break. With Woven cotton fabrics, the extension or elongation at break is in the neighborhood of 13%.

(1a) A cotton poplin, which had been singed, desized, bleached and mercerized, was in wet state subjected to the following micro-length stretching treatment in weft direction (the weft yarns were weaker than the warp yarns), which resulted in a degree of stretching and hence an increase of the width of 9%. The poplin was led across curved expander rolls of the customary type to keep it wide and uncreased, and then passed between two mating metal bowls which on their surfaces had grooves alternating with ridges, the ridges of one bowl penetrating into the grooves of the other (without touching it) to a predetermined depth. The pitch of the ridges per inch was 0.177 (5.6 teeth/"), the penetration was set to give a degree of stretching of 9%. After passing between the grooved bowls, the poplin had about the same width as before, but it had in warp direction grooves alternating with ridges, which when pulled out to flatten the surface gave a width of 98 cm. The fabric was then dried to that width.

The poplin then was subjected to a crosslinking treatment by padding in a bath containing 160 grams/liter of dimethylolpropylene urea, 14 grams/liter of zinc nitrate and 30 grams/liter of a polyethylene softener drying (the width of 98 cm. obtained by micro-length stretching was again maintained) and curing at 150 C. during 4 minutes.

(1b) The same poplin fabric for comparison purposes was crosslinked as described above without previous micro-length stretching, the finished width being 90 cm.

(2a) A light-weight cotton fabric (percale) was singed, desized, bleached, mercerized and dyed and then without drying subjected to micro-length stretching as described in Example 1a, the degree of stretching being 11%. After drying to a width of 100.5 cm. it was crosslinked by padding in a solution of 120 g./l. formaline (36% formaldehyde by weight), 24 g./l. of a metal salt catalyst and 30 g./l. of a polyethylene softener, drying to 100 cm. width, and curing during 4 minutes at 130 C. To remove unreacted formaldehyde and the catalyst, the fabric was rinsed in slack state.

(2b) The same fabric was treated as described in Example 2a, but prior to micro-length stretching the angle between warp and filling yarns was changed to 75 by known means, the direction of stretching thus not being completely parallel to the weft yarns. The degree of stretching was 11.5% (width 100.5 cm., formerly 90 cm.). During subsequent drying the right angle between warp and filling yarns was restored. The fabric was then crosslinked as described in Example 2a.

The fabric mentioned in Example 2a was crosslinked as described without having been subjected to micro-length stretching.

(3a) A cotton poplin was subjected to micro-length stretching as described in Example 1a after the usual pretreatments, with degree of stretching being. 9.5% (width increase from 90 cm. to 98.5 cm.). After drying to the same width the poplin was slack mercerized (dimensions in warp direction unchanged, width decrease 8.5% sodium hydroxide B). After neutralizing, rinsing and drying to 91 cm. the cotton was crosslinked as described in Example 1a.

ment in the presence of caustic, i.e. in a highly swollen state. The width increase was 5%, which was maintained during subsequent neutralizing, rinsing, drying and crosslinking treatments (dimethylolpropylene urea as described in Example 1a).

(3c) The same poplin was after the pretreatment slack mercerized (shrinkage 8% in weft direction (neutralized and rinsed; it was then subjected to micro-length stretching in swollen state using the method described in Example la (width increase 9%), dried to the maximum width obtained and crosslinked as in the preceding examples.

(3d) The same poplin after being pretreated was slack mercerized as described in Example 3c, but after being neutralized it was dried to the maximum width obtained and then padded in the crosslinking bath mentioned in Example 1a. In wet state (i.e. in the presence of the' unreacted cross-linking agent) the fabric was then subjected to micro-length stretching as described in Example la, dried to the maximum Width obtained (degree of stretching 10%) and crosslinked under the conditions given in Example 1a.

(3e) The same poplin was treated as described in Example 30, but micro-length stretching took place prior to neutralization. The width increase obtained after flattening the fabric (pulling out the groove/ridge structure which had formed during micro-length stretching) during drying was 9%. The fabric was then dried and crosslinked as described in Example 3d (i.e. applying a second micro-length stretching treatment in the presence of the crosslinking agent).

(3f) The poplin mentioned in Examples 3a-3d was crosslinked as described after being pretreated without any micro-length stretching treatment (finished width cm.).

(4a) A light-weight cotton fabric (cambric) after singeing, desizing, mercerizing and bleaching was padded in dry state in 140 g./l. of formaline (36% formaldehyde by weight), 24 g./l. of a metal salt catalyst and 30 g./l. of a non-ionic softener and without drying subjected to micro-length stretching in weft direction as described in Example 1a. The width increase was 10 cm. (from 90 cm. to cm.), which was virtually maintained during subsequent drying (width 100.25). Crosslinking was effected by heating to for 4 minutes. The cotton fabric then was rinsed in slack state first in an alkaline, then in a neutral bath and dried (width 97 cm.) and subsequently compressively shrunk by mechanical means.

(b) The same cotton fabric as in Example 4a after having been pretreated was not subjected to micro-length stretching, but to stretching by conventional means according to U.S. Pat. 2,977,665, i.e. it was stretched during crosslinking by pulling at both selvages in a tenter frame. The maximum width which could be obtained without tearing off the selvages or damaging the fabric otherwise,

was 95 cm. (starting width 90 cm.). The crosslinking agent and the curing temperature was exactly the same as in the process according to Example 4a.

(4c) The same cotton fabric was crosslinked as described in Example 4a, but without any stretching treatment (finished width 90 cm.).

(5a) A cotton fabric (percale) was subjected to microlength stretching in Weft direction as described in Example 1a after it had been pretreated as usual. Prior to 17 propylene urea in the presence of 14 g./l. zinc nitrate and 30 g./l. anionic softener at 150 C. for 4 minutes.

(5b) To the same fabric the crosslinking formulation given in Example 5a was applied, and the fabric was jected to a micro-length stretching as described in Example la in wet state, and subsequently crosslinked in wet state according to Example 1 of the British patent specification 894,195. Still in wet state, it was subjected then subjected to a micro-length stretching treatment in 5 to a second length stretching treatment and crosslinked in weft direction in the presence of 40% water per weight dry state as described in Example la. of the fabric. The width obtained and maintained during (9b) The same poplin was crosslinked first in wet drying and curing was 98.5 cm. state, then in dry state as described in Example 9a, but

(5c) The same percale was padded in the cross-linkwithout any micro-length stretching. ing bath mentioned in Example 5a and then subjected not 10 (10a) A cotton broadcloth after the customary preto micro-length stretching, but to stretching over the treatment in wet state was subjected to micro-length whole width during crosslinking according to U.S. Pat. stretching as described in Example la and dried (main- 2,977,665. The maximum width obtainable without teartaining the maximum width obtained). It was then crossing off selvages was 95 cm. linked by applying 200 g./l. of an acetal of formaldehyde (6) A cotton poplin after being pretreated as usual (Quaker Reactant 16) and 25 g./l. of magnesium chlowas subjected to a micro-length treatment as described ride and curing at 140 C. for 5 minutes. The fabric in Example la. Two strands of the fabric were, however, then was washed in rope form without tension, top run through the grooved rollers simultaneously one on softened and dried. top of the other. The production rate in the stretching (10b) The same broadcloth was pretreated as usual step thus was doubled. 20 and then padded in a triazinone crosslinking agent (Fix- (7) The cotton poplin mentioned in Example 1a was apret TM, Badische Aniliri and Sodafabrik, Ludwigshafen, subjected to micro-length stretching as follows: the Germany, 140 g./l.), 12 g./l. magnesium chloride and fabric was in wet state pressed between one grooved bowl 20 g./l. of an anion-active softener. The fabric was then (pitch of grooves as stated in Example 1a) and an endin wet state subjected to micro-length stretching as deless rubber belt which by tensioning was pressed against scribed in Example la and dried, the width thereby being the grooved bowl and hence penetrated into its grooves. increased by 13.3% (from cm. to 102 cm.), curing The resulting degree of stretching was 8%. was effected at 140 for 4 minutes. The fabric then was (8a) A cotton broadcloth was pretreated as usual rinsed and dried. and then subjected in wet state to micro-length stretching 10 The same broadcloth was crosslinked with as described in Example 1a. The width increase was 10.5 3 Quaker Reactant 16 as described in Example 0 but cm. (from 84 cm. to 94.5 cm.). The fabric was then Without any stretching treatment. crosslinked in Swollen State y Padding in of (11a) A cotton poplin after the usual pretreatments Mykon Lubricant PB in Sulfuric acid, batching, stqring was subjected to micro-length stretching as described for 16 hours at room temperature, rinsing, neutrahzing in Example 1 in Wet State, dyedI again subjected to and y 35 micro-length stretching and dried again to the maximum (8b) The same fabric was treated as described in width obtained by micro-length stretching. Example 8a, but micro-length stretching took place only The width increased from 90' to 9-8 cm. The fabric then immediately after padding on the crosslinking solution. was crosslinked by applying g./l. dimethylol-ethylene The fabric was then flattened by stretching slightly, 40 urea, 14 g./l. magnesium nitrate and 25 g./l. of a poly batched, stored, neutralized and dried as in Example 8a. ethylene softener, drying to the width previously obtained (8c) The same fabric was crosslinked in swollen state and curing for 3 minutes at as described in Example 8a, but without any stretching (11b) The same poplin was pretreated, dyed and crosstreatment. linked as described in Example 11a, but without any (9a) A cotton was pretreated as usual, then submicro-length stretching.

TABLE I Tensile strength Flex Wash and Area (loss in Tearing abra- Creasing wear increase, Ex. Fabric Cross linking agent Stretching treatment percent) 1 strength 2 sion 3 angles rating 5 percent (1a) Cotton poplin DMPU M.l. (r) 19.5(20. 5) 250 4 7.5 (lb) do Same as above 13. 5015.0) 255 4 (4a)-.. Cotton cambric Formaldehyde M.l. (f) 8.5(35. 0) 280 4(0. 5) 8 (4b) d0 d0 Agcgglbgg 7U.S. Patent 6.0(85. 0) 275 4(0. 5) 4 (4c) .110 do Noiie.' 5.5(s0.0 275 4 0.5

(5a)... Cotton percaie CMPU M.l. (i) 12. 0(11. 0) 260 3-4 10 (5b) .d0 Same as above Same as above 9. 5(30. 0) 250 3-4 8 (5c) do do Accord. to U.S. patent 7. 5(45. 0) 245 3-4 4 (6).... Cotton poplin DMPU M.l. (t) 19.0(20. 5) 250 4 7 (7) ..d0 Same as above Same as above 19. 5(2(). 0)

See footnotes at end of table.

TABLE I-Continued Tensile strength Wash and (loss in Tearing Flex abra- Creasing wear Area in- Ex. Fabric Cross linking agent Stretching treatment percent) 1 strength 3 sion 3 angles rating 6 crease.

(8a) Oottou Wet cross-linking do 3-4 81) do do do 34 (80)... Cotton percale do None 3-4 (9a) do Wet cross-linking M.l. (f) 4-5 RlunkS dry crossing.

(9b) do do None 11. (55. 0) 255 4-5 (10a) Cotton broadcloth- Acetal M.l. (t) 17. 0(20. 0)

10b) do Triazinone Same as above 18. 0(15. 0)

(10c) do Acetal None 14.5(35.0)

(11a) P0plin DMEU M.l. (i) 24.5(9 0) 500 275 (11b) do Same as above None 15. 5(41. 5) 5 0 280 1 Tensile Strength: Determined in stretched direction strips 1" wide, 4 long. Figures mean kilograms. In parenthesis: Loss of tensile strength in stretched direction caused by treatment.

2 Tearing Strength: Elmendori tearing strength tester. Values given for stretched direction only C) Abrasion Resistance: Stoll Quartermaster abrader, flex abrasion (load 3 lbs), values given for stretched direction only 4 Creasing Angles: Sum of warp and filling creasing angles determined according to ASTM D 1255-60 T. dir gVaSlEg-nd Wear Rating: Determined according to AATC O Tentative Test Method 88-1961 T. In parenthesis shrinkage due to washing in stretched ec on B Area Increase: Increase of area due to stretching treatment, area of unstretched sample-100%.

7 USP 2,977,665: Process for increasing dimensional stability at improved tensile strength, characterized by crosslinking under tension. i.e. stretching in the presence of crosslinking agents, no micro-length stretching.

8 M.l. (i): Micro-length stretching in filling direction.

(*) Of course determined in the same direction in the case of unstretched samples.

In the foregoing description and in certain of the exbe positioned in any of the grooves in either of the amples reference has been made to the abolition or subgrooved rolls in a pair as by stretching them over the stantial abolition of the incorporation of the yarns which lands or by making them discontinuous rather than endextend in the direction in which the stretching force is less, as described above. In the latter event they may be exerted. That is, the wavy or sinuous shape frequently fitted into the grooves and held by any suitable means. assumed by the yarns extending in both directions as a Second, the ability to vary the extent of inter digitation result of the crossing of the yarns in the textile material of the lands 36 and 38, for example, over a wide range is substantially pulled out of the yarns which extend in to produce differing degrees of stretch while still maintainthe direction of stretching and the wavy shape of the ing a firm grip on the outer, longitudinal edges of the web. yarns extending in the other direction is accentuated. In Th e ond feat re flow from the u e of yieldable maorder that this may occur it is essential that the yarns terial for the rings 44 and the provision of rings 44 having which cross those which are to be stretched shall not be cross-sectional dimensions such as to be pressed firmly under suflicient tension to defeat the straightening of the by opposed lands whether the rolls 20, 22 are spaced yarns which are being stretched. Thus, when a flat fabric relatively far apart or are caused to mesh 1 consisting or Warp Yarns ruhhrhg lengthwise or the rabrrc In certain cases it may be desired to stretch the fabric and Wsrt or Woof Yarns r urrhrhg transversely or the rabr 1c lengthwise in addition to the stretching thereof widthwise is subjected to micro-length stretching, in accordance with in accordance with this invention In such cases the this invention transversely or the fabric: the warp Yarns lengthwise stretching should be performed either before should not be placed under substantial tension lengthwise or ft the id h i tretching and preferably such of the fabric at the time the transverse stretching occurs. lengthwise tensioning f the f b i as is required for The apparatus disclosed in this specification is espe- 45 lengthwise stretching should not be applied to the fabric cially well adapted for stretching of fabrics in the manner at the time it is passing through the widthwise stretching discussed in the preceding paragraph. Referring ot FIG. 1 operation. The lengthwise stretching may be performed by it should be pointed out that the textile web 10 need not any suitable means, for example by endless rubber belts be placed under longitudinal tension y greater n engaging opposite surfaces of the fabric and which are that required to feed it through the Pairs of grooved r0118 passed through the nip of opposed driven rolls. At the 20, 22 and 30, 32 and very little tension is required for this nip the ubb r b lt are di t rted nd tret hed lengthpurpose. At least one of the grooved rolls in each pair wise thus stretching the fabric sandwiched therebetween. is driven and it is the rotation of such roll which serves to An example of fabric treatment as just described is advance the web through the pair of rolls. The force as follows: developed for transverse stretching results from deflection (12) A cotton fabric (cambric) was Subjected to the of h h? above and below the Orrgrhal Plane or the following treatments after the customary preliminary fabric as It Is engaged by lands and 38 of the treatment (singeing, desizing, bleaching, mercerizing): grooved rolls 20, 22 and thus is not derived from forces (a) Reticulation Without Small Zone elonagtion applied longitudinally of the web. This is in contrast with (b) Small zone elongation in the Warp direction reticuthe usual operation of a bowed roll or a spirally threaded lation spreader roll (like the rolls 14, 28 and 34 shown herein) (6) Small zone elongation in the warp direction in connection with which any force which causes spread- Sequenfly in the Woof direction reticulation ing of the fabric widthwise is derived from the forces The reticulation was done with 160 gm./liter dimethapplied longitudinally of the web to force it to go over the ylhhcyclopropylene urea usual. commercial dbowed rolls of Splral rollsnot), 50% of a 30% usual, polyethylene softener and 14 The apparatus shown in the drawings is useful, not only gm. per liter zinc nitrate by finishing, drying at 90 dog, in connection with the specialized stretching of fabrics as condensing for 4 minutes at 150 deg. just discussed, but also is useful in spreading or stretching The small zone elongation in the warp direction took of any sheet material. While grooved rolls have been place by pressing between two elastic bodies, namely by used in the past for spreading certain materials it is betreatment of the wet fabric between two endless rubber lieved that none of the prior art structures have provided bands, which were strongly pressed against each other any equivalent of the edge gripping devices shown herein. at one place by means of two cylinders. Both cylinders Particular features of the elastically deformable rings 44 were driven and in turn drove the rubber bands. Due to are first, the ability which they provide for handling of the compression of the two rubber bands there set in a webs of various widths. In this respect the rings 44 may surface enlargement in the running direction of the rubber a b c Tensile strength (untreated) (kg):

K 19.5 19.5 19.5 S 24. 24. 0 24. 0 Elongation in warp direction, percent ...r. 6 6 Elongation in woof direction, percent 8 Tensile strength (after), K .0 19. 17. 5 Retioulation (kg), S 0 20. 0 Strength loss due to reticulation percent:

I claim:

1. In apparatus for effecting micro-length stretching of webs of material transversely of the length of said webs comprising at least first and second pairs of cylindrical rolls, each of said rolls having a series of circumferentially extending axially spaced grooves and lands, means mounting each pair of said rolls in parallel intermeshing relation so that the lands of one roll extend into the grooves of the other roll in spaced relation thereto, adjustable means for each pair of rolls for moving the rolls radially relative to one another to establish the desired amount of extension of the lands into the grooves of the rolls, means gripping longitudinally extending spaced parallel zones of said Web as the web moves between the nip of the rolls of each pair, and means for rotating said rolls at a predetermined angular rate in a direction to advance the Web through the nip of the rolls to effect a predetermined elongation velocity and in a manner to maintain a minimum tension on the web in a longitudinal direction, means for transferring said web from said first pair of intermeshing rolls to said second pair of intermeshing rolls including means for spreading and smoothing said web before it enters said second pair of rolls and for guiding said web to said second set of rolls in such manner that at least a substantial part of each portion of said Web which was not in contact with a land in said first pair of intermeshing rolls is brought into contact with a land in said second pair of intermeshing rolls.

References Cited FOREIGN PATENTS 424 1866 Great Britain 2663 2,421 1885 Great Britain 2663 5,621 1886 Great Britain 2663 8,230 1900 Great Britain 2663 14,608 1884 Great Britain 2663 19,078 1897 Great Britain 2663 ROBERT R. MACKEY, Primary Examiner US. Cl. X.R. 2651;2876 E 

